1. Field of the Invention
This invention relates to a word-organized, content-addressable memory, comprising a first input for inputting a key word, a second input for inputting a mask word for the selective deactivation of a part of the input key word by masking, an output for outputting a data word stored in a word location, first means for comparing a non-masked part of a key word with a corresponding part of a data word stored in a word location, and second means for indicating, for each word location, correspondence detected by said first means and for activating said output for outputting data from a word location for which correspondence occurs.
2. Description of the Prior Art
A memory of this kind is known from the article by J. Barlett et al, Associative Memory Chips: fast, versatile and here, Electronics (700,817) pages 96-100; for example, the memory 4102 by Fairchild Semiconductor Corp. described on page 97 which comprises four words of four bits. For these 16 bits, the integrated circuit of said memory comprises twenty-four connection pins, i.e.:
(a) four connections for an address, so that the data can also be addressed in the manner of a random access memory (RAM); PA1 (b) four connections for a descriptor word which indicates the keyword; PA1 (c) four connections for enable data, i.e. concerning the mask word; (the bit locations masked by the mask word are not taken into account for the comparison); PA1 (d) four connections for a correspondence signal, i.e. one for each separate word; PA1 (e) four connections for the parallel output of the data of a four-bit content word; PA1 (f) one connection for the inverted correspondence signal; PA1 (g) one connection for a write enable signal; and PA1 (h) two current connections; thus in total 24 connections.
The number of connection pins for each data bit stored is calculated as (5n+4) divided by n.sup.2 for a square matrix of n.times.n bits, which is comparatively high. On a matrix comprising 40 connection pins, at the most 7.times.7 bits could be accommodated.